Case Report: Misleading Serological Diagnosis of Paracoccidioidomycosis in a Young Patient with the Acute Form Disease: Paracoccidioides brasiliensis or Paracoccidioides lutzii?

Fast and cost-effective protocol to produce Paracoccidioides spp. antigens

INTRODUCTION

The existing methods for Paracoccidioides spp. antigen production are problematic in terms of standardization, specificity, stability, repeatability, and reproducibility.

OBJECTIVE

To optimize the methodology for Paracoccidioides spp. antigen production and evaluate its applicability in paracoccidioidomycosis immunodiagnosis.

MATERIALS AND METHODS

The antigens were obtained from Paracoccidioides lutzii isolates (01, 66, and 8334), Paracoccidioides brasiliensis sensu stricto (113), and Paracoccidioides restripiensis (B-339). These fungi were grown at 36 °C ± 1 °C, on modified Fava-Netto agar, according to Freitas et al. (2018). Paracoccidioides lutzii antigens were obtained after , 10, and 20 days of culture, whereas P. brasiliensis and P. restripiensis antigens were obtained after 10 days. Antigens were evaluated in natura, 10 and 20 times concentrated. Antigenic capacity was evaluated using a double immunodiffusion assay against serum samples from patients with paracoccidioidomycosis, histoplasmosis, and aspergillosis, and random blood donors.

RESULTS

Cross-reactivity between Paracoccidioides spp. antigens was observed when P. brasiliensis, P. restrepiensis antigens, and P. lutzii antigens were evaluated with the polyclonal antibodies against P. lutzii and P. brasiliensis, respectively. No cross-reactivity was obtained for polyclonal antibodies against Histoplasma capsulatum, Aspergillus fumigatus, and random blood donors. The proposed protocol allowed stable, repeatable, and reproducible genus-specific antigen production at a low cost and in a short cultivation time.

CONCLUSION

The proposed protocol allowed us to obtain genus-specific antigens that can be developed and reproduced in all laboratories in Brazil and South America, where paracoccidioidomycosis is a neglected disease, contributing to an early diagnosis, especially in endemic regions, regardless of the species.

Immunologic Diagnosis of Endemic Mycoses

The endemic mycoses blastomycosis, coccidioidomycosis, histoplasmosis, paracoccidioidomycosis, cryptococcosis, sporotrichosis, talaromycosis, adiaspiromycosis, and emergomycosis are mostly caused by geographically limited thermally dimorphic fungi (except for cryptococcosis), and their diagnoses can be challenging. Usual laboratory methods involved in endemic mycoses diagnosis include microscopic examination and culture of biological samples; however, serologic, histopathologic, and molecular techniques have been implemented in the last few years for the diagnosis of these mycoses since the recovery and identification of their etiologic agents is time-consuming and lacks in sensitivity. In this review, we focus on the immunologic diagnostic methods related to antibody and antigen detection since their evidence is presumptive diagnosis, and in some mycoses, such as cryptococcosis, it is definitive diagnosis.

Comparison of clinico-epidemiological and radiological features in paracoccidioidomycosis patients regarding serological classification using antigens from Paracoccidioides brasiliensis complex and Paracoccidioides lutzii

Genotyping of the genus Paracoccidioides showed its diversity and geographical distribution. Four species constituting the Paracoccidioides brasiliensis complex and Paracoccidioides lutzii are etiological agents of paracoccidioidomycosis (PCM). However, there are no studies comparing the clinical and epidemiological aspects between PCM caused by the P. brasiliensis complex and by P. lutzii. Demographic and clinical data from 81 patients with PCM-confirmed by mycological and/or histopathological examination-from Mato Grosso do Sul state (Brazil) were studied. All patients underwent serology by immunodiffusion with antigens obtained from the P. brasiliensis complex (ExoPb and gp43) and Cell Free Antigens obtained from P.lutzii (CFAPl).The cases were classified regarding their serological profile into three groups: G1: PCM patients seropositive to ExoPb and/or gp43 and seronegative to CFAPl (n = 51), assumed to have PCM caused by P. brasiliensis complex; G2: PCM patients seronegative to gp43 and seropositive to CFAPl (n = 16), with PCM caused by P. lutzii; and G3: PCM patients seropositive to ExoPb or gp43 and seropositive to CFAPl (n = 14), with undetermined serological profile, was excluded from the analyses. The Fisher's exact test or the Mann-Whitney U test, and cluster analysis according to Ward's method and Euclidean distance were used to analyze the results. Patients with serological profile suggestive of P. lutzii lived predominantly in municipalities in the Central and Southern regions of the state, while those with serological profile indicative of the P. brasiliensis complex were distributed throughout the state. No differences were found between the two groups regarding gender, age, schooling, rural work, clinical form, severity, organs involved, intensity of pulmonary involvement, degree of anemia, erythrocyte sedimentation rate values, and therapeutic response. PCM patients with serological profile suggestive of P. lutzii and PCM patients with serological profile indicative of P. brasiliensis complex showed the same clinical and radiological presentations.

Clinical features and genetic background of the sympatric species Paracoccidioides brasiliensis and Paracoccidioides americana

Introduction

The agents of paracoccidioidomycosis, historically identified as Paracoccidioides brasiliensis, are in fact different phylogenetic species. This study aims to evaluate associations between Paracoccidioides phylogenetic species and corresponding clinical data.

Methods

Paracoccidioides strains from INI/Fiocruz patients (1998–2016) were recovered. Socio-demographic, epidemiological, clinical, serological, therapeutic and prognostic data of the patients were collected to evaluate possible associations of these variables with the fungal species identified through partial sequencing of the ADP-ribosylation factor (arf) and the 43-kDa-glycoprotein (gp43) genes.

Results

Fifty-four fungal strains were recovered from 47 patients, most (72.3%) infected in Rio de Janeiro state, Brazil. Forty-one cases were caused by Paracoccidioides brasiliensis and six by Paracoccidioides americana (former PS2). P. brasiliensis was responsible for severe lymph abdominal forms, whereas patients infected with P. americana presented a high rate of adrenal involvement. However, no statistically significant associations were found for all variables studied. P. americana presented 100% reactivity to immunodiffusion, even when tested against antigens from other species, while negative results were observed in 9 (20%) cases caused by P. brasiliensis, despite being tested against a homologous antigen.

Conclusions

P. brasiliensis and P. americana are sympatric and share similar clinical features and habitat, where they may compete for similar hosts.

Paracoccidioidomycosis (PCM) is a severe systemic mycosis caused by different phylogenetic species. According to previous studies, these species could have an impact in PCM clinical features. This study aims to investigate possible associations between Paracoccidioides species and corresponding clinical data. The fungal strains from the patients were recovered, whereas their clinical data were collected to evaluate possible associations of these variables with the fungal species identified through DNA sequencing. Fifty-four fungal strains were recovered from 47 patients, most infected in Rio de Janeiro state, Brazil. Forty-one cases were caused by Paracoccidioides brasiliensis and six by Paracoccidioides americana. P. brasiliensis was responsible for severe clinical forms, and patients infected with P. americana presented a high rate of adrenal involvement. However, no statistically significant associations were found for all variables studied. P. brasiliensis and P. americana share similar clinical features.